Page:Miscellaneous Papers on Mechanical Subjects.djvu/179



The number of muskets made in the year 1852 amounted to 19,800.

75. Coast Survey Office, Washington. — Workshops are attached to the Coast Survey Office, where copies of the standard weights and measures of the United States are made. The office supplies the capital of every State in the union, in addition to the standard weights and measures, with three very accurate balances.

No. 1 is constructed to weigh from 50 lbs. down to 10 lbs.

No. 2 to weigh from 10 lbs. to 1 lb.

No. 3 to weigh from 1 lb. to $1/10000$ oz.

The estimated cost of the three is $4,600 about 900l. The latter balance was tested, and deflected by the $1/10000$ oz. In weighing 1 lb. the effect of the addition of $1/200$ grain was instantly visible.

When the balance is not in use, the beam is made to descend by means of a screw, so that two external cones, placed on its under side, rest in two internal cones fixed on the supporting frame. Two steel discs attached to the chains of the scales are, by the same screw, made to descend, and rest upon the frame. Thus the whole balance is supported, and there is no continued strain on the knife edges.

A lever worked by hand acts upon the two